Martin Rule Curve Study

Ashley McVicar, APC

Maurice James, Water Resources Consulting LLC

Martin Rule Curve Study

• Design Flood Study Approach– Determine flood to model for the 100 year

design flood – Replicate operations for the actual flood event

in an operation spreadsheet• Model looked at both change in inflow and elevation to

determine number of gates to open limited by 2 an hour

– Compare Results

Martin Rule Curve Study

• APC Flood Frequency Analysis– Model developed by US Army Corps of

Engineers – Hydrologic Engineering Center in Davis, CA

– Utilizes the Corps 1939-2001 unimpaired flow database created as part of the ACT Comprehensive Study

– Submitted to the COE by APC in November 2005

Martin Rule Curve Study

• Martin flow– 100 yr flow unregulated = 130,000 cfs-days– March 1990 flow unregulated = 125,019 cfs-

days (96% of 100 year flood)– March 1990 inflow regulated used in Martin

Rule Curve evaluation (with Harris and Martin in place) = 92,307 cfs-days (71% of 100 year unregulated flood)

Wadley Annual Peaks

0%

5%

10%

15%

20%

25%

30%

1 2 3 4 5 6 7 8 9 10 11 12

Month

Per

cen

t

81 Years of Record

EL 480 ft.

EL 490 ft.

72%

Current Martin Flood Control Guidelines

Martin Rule Curve Study

• General Assumptions– Martin Turbine Capacity = 16500 (based on observed

data from recent past events)– Yates Turbine Capacity = 12400– Thurlow Turbine Capacity = 13200– 20 lift gates

• 6 alternate (based on opening schedule)• 11 adjacent• Assumed we would not use last 3 gates as they flood out the

powerhouse

– Ability to open 2 spillway gates an hour to be conservative

Martin Reservoir Model Calibration

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

3/15 3/16 3/17 3/18 3/19 3/20 3/21 3/22 3/23 3/24

Date

Dis

char

ge

cfs

483.0

484.0

485.0

486.0

487.0

488.0

489.0

490.0

Ele

vati

on

ft.

(M

arti

n D

atu

m)

Model Discharge

Actual Discharge

Inflow

Model Elevation

Actual Elevation

Martin Rule Curve Study

• Design Flood Evaluation– Operational criteria set forth in model

accurately replicated historical conditions

Martin Rule Curve Study

• Evaluation of Winter Pool of 480’ vs. 483’– Used current operational criteria set forth by

March 1990 flood historical operations and began pool at both 480’ and 483’

– No operational criteria was changed

Martin Reservoir

475

477

479

481

483

485

487

489

491

493

495

Elev

atio

n (M

artin

Dat

um)

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Martin Reservoir 480 vs. 483 Model Simulation

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

15 16 17 18 19 20 21 22 23 24

Date

Dis

char

ge

cfs

478

480

482

484

486

488

490

492

Ele

vati

on

ft.

(M

arti

n D

atu

m)

480 Discharge

483 Discharge

Inflow

480 Elevation

483 Elevation

Martin Rule Curve Study

• Elevation 480’ vs 483’ Results– Martin pool kept below top of easement

elevation 490 for both – Beginning winter pool elevation of 483’ results

in earlier releases as well as approximately 25-30k higher discharge during the peak

• Results routed with HEC-RAS model downstream to determine effects

Tallapoosa Profile

150

155

160

165

170

175

180

185

190

195

200

205

210

215

220

0 5 10 15 20 25 30 35 40 45 50 55

Tallapoosa River Mile

Max

imu

m E

leva

tio

n f

t. m

sl Initial Pool-480

Initial Pool-483Montgomery Water

Works gage

Milestead gage

Tallassee gage

Alabama River Thurlow Dam

Martin Rule Curve Study

• Results– Elevations downstream result in a 1’ – 3’ higher

elevation downstream to Alabama River.– Corps of Engineers uses FEMA’s requirement of no

increase of peak elevation downstream– FERC defers to the Corps for flood analysis– FERC would require a full analysis of impacts of

proposed vs. current operation including• Environmental• Erosion• etc

Martin Rule Curve Study

• Further Study during Relicensing Required– Look at different operational plans

• Pass % of inflow in zones• Open gates based on a lower starting elevation

– Look at different winter pool elevation and/or shape of Rule Curve

• 484’• Change in summer pool duration

– Further evaluate downstream flood & environmental impacts and present these effects and any mitigation to FERC

– FERC will then evaluate and balance the proposal